Some choice quotes from a fascinating article from the New York Times science section:
Most people think liars give themselves away by averting their eyes or making nervous gestures, and many law-enforcement officers have been trained to look for specific tics, like gazing upward in a certain manner. But in scientific experiments, people do a lousy job of spotting liars. Law-enforcement officers and other presumed experts are not consistently better at it than ordinary people even though they’re more confident in their abilities.
The common-sense notion that liars betray themselves through body language appears to be little more than a cultural fiction
There is no Pinocchio’s nose — no one cue that will always accompany deception
I was particularly pleased to see the research debunking the old NLP upward eye movement factoid cited yet again. When millions of dollars every year are spent in the USA on security theatre that relies on body language signals that are actually meaningless, and furthermore these discredited notions are being taught all over the world in behavioural training seminars (including those for law enforcement officers), then it’s important to keep on hammering home the facts.